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To evaluate long-term real-life results of dasatinib therapy among chronic phase chronic myeloid leukemia patients resistant or intolerant to imatinib, we retrospectively analyzed data of 118 patients treated in centers participating in the database INFINITY. With median follow-up of 37 months, estimated 5-year cumulative incidences of complete cytogenetic and major molecular responses were 78% and 68%, respectively. The estimated 5-year probability of overall survival (OS) and event-free survival (EFS) were 86% and 83%, respectively. Both OS and EFS were significantly improved among patients with

PURPOSE Despite the successes achieved in chronic myeloid leukemia (CML) with tyrosine kinase inhibitor (TKI) therapy, resistance remains an obstacle. The most common mechanism of resistance is the acquisition of a point mutation in the BCR-ABL kinase domain. Few studies have reported African patients with CML in regard to such mutations. We here report the types of BCR-ABL mutations in Ethiopian imatinib-resistant patients with CML and their outcome. PATIENTS AND METHODS Patients with CML with a diagnosis of imatinib resistance who were tested for BCR-ABL mutation between 2014 and September 2019 were included. RESULTS A total of 962 cases of CML on imatinib therapy were reviewed and 164 cases of failure were found. Of these, only 31 cases (19%) had mutation analysis performed. Most cases (94%) were secondary failures. At the time of CML diagnosis, the median age was 33 years and the majority presented with features of advanced-phase disease. Of the 31 patients, 22 mutations were found (65%). The types of mutations detected were as follows: non–P-loop mutations 36% (11), P-loop mutations 13% (four), and alternatively spliced BCR-ABL variants 23% (seven). The splice variant frequently detected was BCR-ABL35INS (20%). Twenty-six of the 31 patients (84%) were switched to second-line TKIs, whereas in four patients (13%), imatinib dose escalation was done. Overall, the outcome revealed that 16 patients (52%) were alive with complete hematologic response, whereas 12 patients (39%) had died. All patients who expressed BCR-ABL135INS were treated with second-line TKIs, and two of them (33%) had died because of disease progression. CONCLUSION In Ethiopia, CML affects the young and point mutations were frequently detected in imatinib-resistant patients. BCR-ABL1 35INS was also prevalent and associated with disease progression.

Chronic myeloid leukemia (CML) patients who have BCR-ABL T315I mutation, usually present in the advance phase of the disease with overall survival (OS) shorter than those without the mutation. This study aimed to determine the prevalence of T315I mutation amongst imatinib mesylate (IM) resistant CML patients and to compare the OS between T315I-mutated and non-T315I-mutated patients. Sixty consecutive CML patients who were treated with IM for at least 18 months and their treatment responses, were recorded. The mutation analysis was done using allele-specific oligonucleotide reverse transcriptase-polymerase chain reaction (RT-PCR) assay followed by direct sequencing technique. Forty-two patients (70%) were found to have IM-resistance. Five out of 42 patients had detectable T315I mutation. Median OS of IM-resistant T315I-mutated patients was 96 months (95% CI:54-138) compared to 84 months (95% CI:48-120) in non T315I-mutated patients, although this was found to be statistically insignificant (p = 0.43). The present study showed a higher prevalence of T315I mutation as compared to a few local studies. Median OS of T315I-mutated patients were observed to be longer than non-T315-mutated patients. Further studies encompassing larger cohort of patients are required to confirm this finding.

Dasatinib is a highly effective second-generation tyrosine kinase inhibitor used to treat chronic myeloid leukemia (CML). In 2007, a pivotal phase-2 study of dasatinib as second-line treatment was initiated in 140 Chinese CML patients. This report from the 4-year follow-up revealed that 73% of 59 patients in chronic phase (CML-CP) and 32% of 25 patients in accelerated phase (CML-AP) remained under treatment. The initial dosage of dasatinib for CML-CP and CML-AP patients were 100 mg once daily and 70 mg twice daily (total = 140 mg/ day), respectively. The cumulative major cytogenetic response (MCyR) rate among patients with CML-CP was 66.1% (versus 50.8% at 18 months), and the median time to MCyR was 12.7 weeks. All CML-CP patients who achieved MCyR after a 4-year follow-up also achieved a complete cytogenetic response. The cumulative complete hematological response (CHR) rate among patients with CML-AP was 64% (16/25), with three CML-AP patients achieving CHR between 18 months and 4 years of follow-up; the median time to CHR was 16.4 weeks. The adverse event (AE) profile of dasatinib at 4 years was similar to that at 6 and 18 months. The most frequently reported AEs (any grade) included pleural effusion, headache, and myelosuppression. These long-term follow-up data continue to support dasatinib as a second-line treatment for Chinese patients with CML.

Predictive markers; Sarcoma; Gastrointestinal stromal tumours Marcadores predictivos; Sarcoma; Tumores del estroma gastrointestinal Marcadors predictius; Sarcoma; Tumors estromals gastrointestinals Background Most patients with KIT-mutant gastrointestinal stromal tumours (GISTs) benefit from imatinib, but treatment resistance results from outgrowth of heterogeneous subclones with KIT secondary mutations. Once resistance emerges, targeting KIT with tyrosine kinase inhibitors (TKIs) sunitinib and regorafenib provides clinical benefit, albeit of limited duration. Methods We systematically explored GIST resistance mechanisms to KIT-inhibitor TKIs that are either approved or under investigation in clinical trials: the studies draw upon GIST models and clinical trial correlative science. We subsequently modelled in vitro a rapid TKI alternation approach against subclonal heterogeneity. Results Each of the KIT-inhibitor TKIs targets effectively only a subset of KIT secondary mutations in GIST. Regorafenib and sunitinib have complementary activity in that regorafenib primarily inhibits imatinib-resistance mutations in the activation loop, whereas sunitinib inhibits imatinib-resistance mutations in the ATP-binding pocket. We find that rapid alternation of sunitinib and regorafenib suppresses growth of polyclonal imatinib-resistant GIST more effectively than either agent as monotherapy. Conclusions Our data highlight that heterogeneity of KIT secondary mutations is the main mechanism of tumour progression to KIT inhibitors in imatinib-resistant GIST patients. Therapeutic combinations of TKIs with complementary activity against resistant mutations may be useful to suppress growth of polyclonal imatinib-resistance in GIST. This work was supported in part by an ASCO Young Investigator Award (CS), a Spanish Society of Medical Oncology Translational Award (CS), Río Hortega-ISCIII CM14/00241 (CS) FERO Foundation (CS), US National Institutes of Health grants 1P50CA127003 (GDD, ES, JAF), 1P50CA168512 (JAF, AME), GIST Cancer Research Fund (JAF, MCH), Life Raft Group (JAF, MCH, SB), V Foundation Translational Grant (MCH), VA Merit Review Award (2I01BX000338–05) (MCH) and the Deutsche Krebshilfe (SB). CS acknowledges to the Cellex Foundation for providing facilities and equipment.

Chronic myelogenous leukemia (CML) is one of the most common cancers in the world. Imatinib is one of the most effective therapeutic strategies to inhibit the BCR-ABL tyrosine Kinase in patients with CML, but resistance is increasingly encountered. Microarray data GSE7114, GSE92624 and GSE97562 were downloaded and analyzed from Gene Expression Omnibus (GEO) to identify the candidate genes in the imatinib-resistant CML cells. The differentially expressed genes (DEGs) were appraised, and the protein–protein interaction (PPI) network was created by using STRING and Cytoscape. We screened a total of 217 DEGs, including 151 upregulated genes and 66 downregulated genes. The enriched functions and pathways of genes include insulin-like growth factor I binding, cysteine-type endopeptidase inhibitor activity involved in apoptotic process, cell adhesion, positive regulation of nitric oxide biosynthetic process and hematopoietic cell lineage. Nine hub genes were appraised and Gene Ontology enrichment analysis revealed that these genes are mainly enriched in cell cycle, peptidase inhibitor activity and cell division. Several genes such as BIRC5, CCNE2 and MCM4 were identified in survival analysis and these genes alteration are significantly associated with worse overall survival and disease-free survival. These genes have the potential to become surrogate markers for a clinical evaluation of imatinib-resistant CML patients. Our results provide potential target genes for diagnosis and treatment of imatinib-resistant CML patients.

Background: Although imatinib can effectively treat gastrointestinal stromal tumor (GIST), some patients are still resistant to it or cannot tolerate the adverse reactions of the drug. This study aimed to investigate potential miRNAs, mRNA and tumor-infiltrating lymphocytes (TILs) associated with the prognosis of imatinib-resistant GIST.Methods: mRNA, miRNA sequencing data and patient clinic traits of primary (imatinib-naive) and imatinib-resistant GIST were obtained from GEO (Gene Expression Omnibus) database. A systems biology approach combining Weighted co-expression network analysis (WGCNA) and differential expression analysis were utilized to detect the imatinib-resistant-related miRNA and gene modules and construct a miRNA-gene network. Tumor-infiltrating immune cells were analyzed by Estimating the Proportion of Immune and Cancer cells (EPIC) and Tumor-Immune System Interactions (TISIDB). miR-539 was measured by qRT-PCR. SPAG5 and APOBEC3B was measured by qRT-PCR and WB. Transforming growth factor (TGF)-β and interleukin (IL)-10 were assessed with enzyme-linked immunosorbent assay (ELISA). The proportions of CD4+ T cells, CD8+ T cells , NK cells and B cells in tumor-infiltrating lymphocyteswere analyzed via flow cytometry (FCM).Results: Two gene modules (brown and yellow) and one miRNA module were associated with the imatinib-resistant. Two hub genes (APOBEC3B and SPAG5) were associated with the imatinib-resistant. Three hub miRNAs were identified to be related to imatinib-resistant (miR-539, miR-376b and miR-18b). G1/S transition of mitotic cell cycle, G2/M transition of mitotic cell cycle, and cell proliferation were common pathways of the gene modules and miRNA module. apolipoprotein B mRNA editing catalytic polypeptide-like 3B (APOBEC3B) and Sperm-associated antigen 5 (SPAG5), which were both target genes of miR-539 was located at the core of miRNA–gene network. APOBEC3B (rho=0.509, p < 2.2e-16) and SPAG5 (rho=0.468, p < 2.2e-16) was positive correlated with the infiltration levels of activated CD4+ T cells. he proportions of CD4+ T cells, and the mRNA and protein relative expression of APOBEC3B and SPAG5 in imatinib-resistant tumor samples significantly increased as compared with tumor samples in imatinib-naive group. Imatinib-resistant tumor samples exhibited significantly downregulation of miR-539 and TGF-β1. Over-expression of miR-539 sensitized imatinib resistant GIST48 cells and increased the secretion of TGF-β1 by inhibiting APOBEC3B and SPAG5.Conclusion: APOBEC3B and SPAG5, the target genes of miR-539 may play as key factor for imatinib-resistant GIST by increasing the proportion of tumor-infiltrated activated CD4+ T cells via TGF-β1. These findings help to advance the understanding of imatinib-resistant GIST and provide potential therapeutic targets.

Ethnopharmacological relevance Ancient mediterranean diet was characterized by consuming the spontaneous forms of Cynara cardunculus L. (CCL), commonly called artichoke. Cultivated and/or spontaneous forms of CC studies have demonstrated that methanol extract of CCL flower and/or cynaropicrin showed remarkable anti-proliferative activity in vitro models of leukocyte cancer cell. Aim of the study Chronic myeloid leukemia (CML) is associated with a reciprocal translocation of the long arms of chromosomes 9 and 22 generating the BCR/ABL fusion gene, translated in the p210 BCR/ABL oncoprotein kinase. This chimeric protein is the target of a kinase inhibitor, imatinib, but the development of mutations in the ABL kinase domain resulting in drug resistance and several approaches to overcoming resistance have been study. In this concern, we investigated the effect of CCL extract on human K562 CML and K562 imatinib resistant (IMAR) cell proliferation and on p210 BCR/ABL expression. Materials and methods Chemical characterization of the CCL extracts was performed by GC/MS analysis and semipreparative RP-HPLC chromatography. Structural characterization of compounds was assessed by 1 H– 13 C NMR and LC/MS analysis. The effects of CCL extracts on the proliferation of K562 CML human cell line and K562 IMAR were screened by MTT assay. The p210 BCR/ABL mRNA and protein expressions were analyzed by qRT-PCR and Western blot techniques respectively. Results We demonstrate that CCL extract affect cell viability of both K562 CML human cell line and K562 IMAR. The biocomponents of CCL were chemical characterized and we identify cynaropicrin and its deacyl derivative having the capability to down-regulate the p210 BCR/ABL oncoprotein. Conclusions Our study suggests that the use of those molecules could represent a novel and promising strategy to potentiate the ability of imatinib or of its analogues to induce cancer growth arrest in CML and to delay or overcome the resistance of CML to chemotherapy.

No abstract available

Imatinib 400 mg is the standard of care for medical treatment of advanced GISTs. In the majority of cases, however, GISTs eventually develop resistance to imatinib. The optimal second line treatment has not been established yet and imatinib dose escalation (800 mg) or sunitinib represent two feasible options. The objective of this retrospective, multi-institutional, study is to analyze the validity of several parameters as possible predictive factors of response to sunitinib after imatinib failure. We reviewed 128 metastatic GISTs treated with sunitinib between January 2007 to June 2017. Primary tumour site, metastatic site, c-KIT/PDGFR-α mutational status, PET-FDG status and type of disease progression to sunitinib were assessed as possible predictive factors of response. This study identifies the gastric site of primary tumor as a predictive factor to sunitinib efficacy in second line setting. The mutational status (GIST WT), the site of metastasis (peritoneum) and the FDG-PET status (negative), although not statistically significant, seem to be elements of increased activity for sunitinib treatment. These results provide the rationale to drive physician for sunitinib choice in second line setting for metastatic GISTs, to improve patients selection and to maximize the benefit from the treatment, on the basis of possible predictive factors of response.

Background: cKIT kinase overexpression and gain-of-function mutations are the critical pathogenesis of gastrointestinal stromal tumors (GISTs). Although the multiple kinase inhibitors such as imatinib, sunitinib, and regorafenib have been approved for GISTs, the acquisition of polyclonal secondary resistance mutations in KIT is still a limitation for GIST treatment. Here we explored the KIT inhibitory activity of axitinib in preclinical models and describe initial characterization of its activity in GIST patient-derived primary cells. Methods: The activities of axitinib against mutant KIT were evaluated using protein-based assay and a panel of engineered and GIST-derived cell lines. The binding modes of axitinib-KIT/KIT mutants were analyzed. Four primary cells derived from GIST patients were also used to assess the drug response of axitinib. Results: Axitinib exhibited potent activities against a variety of cKIT associated primary and secondary mutations. It displayed better activity against cKIT wild-type, cKIT V559D/A/G, and L576P primary gain-of-function mutations than imatinib, sunitinib, and regorafenib. In addition, it could inhibit imatinib resistant cKIT T670I and V654A mutants in vitro and in vivo GIST preclinical models. Conclusion: Our results provide the basis for extending the application of axitinib to GISTs patients who are unresponsive or intolerant to the current therapies.

Korrektur zu 10.1038/s41416-019-0389-6

823 Background: Imatinib is a standard first line treatment for advanced gastrointestinal stromal tumor (GIST); however eventually almost all the GISTs become resistant to imatinib. Secondary mutation in KIT is the most relevant cause of imatinib-resistant, as high as 70% of cases. Sunitinib is standard of care for imatinib-resistant GIST with median progression-free survival (PFS) of 24.6 weeks; however, in a preclinical study sunitinib is not active for approximately half of secondary mutations. Regorafenib is active for some secondary mutations resistant to sunitinib in the preclinical study. Therefore, we conducted a phase II study evaluating regorafenib for imatinib-resistant GIST. Methods: Patients with imatinib-resistant advanced GIST were enrolled. Key eligibility criteria were ECOG PS of 0-1 and adequate organ function. Prior exposure of sunitinib was not allowed. The primary endpoint was PFS rate at 24 weeks. ctDNA for KIT was evaluated prior to regorafenib administration. Results: A total of 38 patients were enrolled as planned. Median age was 64.5 (39 - 80). Twenty-five patients were male. Primary site was stomach in 17, small intestine in 16. Median PFS was 36.3 weeks and PFS rate at 24 weeks was 47.4% (primary endpoint was not met). Best overall response was PR for 6 (16 %), SD for 25 (63 %) and PD for 5 (13 %) patients. Grade 3 or more adverse events (AE) were observed in 25 (66 %) patients. Common grade 3 or more AE were hand-foot-skin reaction (n = 9), hypertension (n = 9), hepatotoxicity (n = 4). ctDNA was evaluated in 32 patients and among them secondary mutations were observed in 15 patients (47%). PFS was shorter (15.6 weeks) in patients with exon 13 mutation than that in patients without second mutation (49.3 weeks, not statistically significant). Conclusions: Regorafenib demonstrated favorable activity in patients with imatinib-resistant GIST as second line therapy with acceptable toxicity. Secondary mutation in KIT might be a predictor of the efficacy of regorafenib. Clinical trial information: UMIN000016115.

Gastrointestinal stromal tumor (GIST) is a refractory disease in need of novel efficacious therapy. The aim of our study was to evaluate the effectiveness of tumor-targeting Salmonella typhimurium A1-R (S. typhimurium A1-R) using on a patient derived orthotopic xenograft (PDOX) model of imatinib-resistant GIST. The GIST was obtained from a patient with regional recurrence, and implanted in the anterior gastric wall of nude mice. The GIST PDOX mice were randomized into 3 groups of 6 mice each when the tumor volume reached 60 mm3: G1, control group; G2, imatinib group (oral administration [p.o.], daily, for 3 weeks); G3, S. typhimurium A1-R group (intravenous [i.v.] injection, weekly, for 3 weeks). All mice from each group were sacrificed on day 22. Relative tumor volume was estimated by laparotomy on day 0 and day 22. Body weight of the mouse was evaluated 2 times per week. We found that S. typhimurium A1-R significantly reduced tumor growth in contrast to the untreated group (P = 0.001). In addition, we found that S. typhimurium A1-R was more effective compared to imatinib (P = 0.013). Furthermore, Imatinib was not significantly effective compared to the control group (P = 0.462). These results indicate that S. typhimurium A1-R may be new effective therapy for imatinib-resistant GIST and therefore a good candidate for clinical development of this disease.

Chronic myeloid leukemia (CML) is a clonal disorder of hematopoietic stem/progenitor cells that is caused by the Bcr-Abl oncoprotein. Clinical resistance to the Bcr-Abl inhibitor imatinib is a critical problem in treating CML. This study investigated the antitumor effect and mechanism of MPT0B169, a new antitubulin agent, in K562 CML cells and their derived imatinib-resistant cells, IMR2 and IMR3. IMR2 and IMR3 cells showed complete resistance to imatinib-induced growth inhibition and apoptosis. Resistance involved ERK1/2 overactivation and MDR1 overexpression. MPT0B169 inhibited the growth of K562, IMR2, and IMR3 cells in a dose- and time-dependent manner. MPT0B169 substantially inhibited the mRNA and protein levels of Bcr-Abl, followed by its downstream pathways including Akt, ERK1/2, and STAT3 in these cells. MPT0B169 treatment resulted in a decrease in the polymer form of tubulin according to Western blot analysis. It triggered cell cycle arrest at the G2/M phase before apoptosis, which was related to the upregulation of the mitotic marker MPM2 and the cyclin B1 level, and a change in the phosphorylation of Cdk1. MPT0B169 induced apoptosis in nonresistant and imatinib-resistant cells via a mitochondrion-mediated caspase pathway. Further study showed that the agent led to a decrease in the antiapoptotic proteins Bcl-2, Bcl-xL, and Mcl-1 and an increase in the apoptotic protein Bax. Taken together, our results suggest that MPT0B169 might be a promising agent for overcoming imatinib resistance in CML cells.

BACKGROUND: Cytogenetic evaluation is required till a complete cytogenetic remission is achieved in chronic myelogenous leukemia (CML) patients on tyrosine kinase inhibitor (TKI) therapy. The routine dual colour fluorescence in situ hybridization (FISH) probes are less sensitive in identifying der(9) abnormalities. BCR/ABL/ASS1 tri-colour dual fusion (TCDF) probe is highly sensitive and specific in identifying der(9) deletions and random signal overlaps. METHODS: Peripheral blood interphase FISH analysis was performed on imatinib-resistant CML patients using TCDF probe. RESULTS: On analyzing 37 adult patients, all had residual Philadelphia (Ph) chromosome. Classic Ph fusion pattern was seen in 33 (89%), derivative chromosome 9 [der(9)] abnormalities in 25 (67.5%) and supernumerary Ph chromosomes in 11 (30%) patients. Coexistence of classical fusion and der(9) abnormalities was seen in 21 patients (57%); and classical fusion, der(9) abnormalities and supernumerary Ph chromosome in 8 patients (22%). None of the patients had BCR-ABL1 gene amplification. There was significant difference in the der(9) abnormal cell percentages between patients with e13a2 and e14a2 transcripts (P = 0.008) and patients with disease transformation (P = 0.007). CONCLUSION: A high frequency of der(9) abnormalities and absence of BCR-ABL1 gene amplification was seen in imatinib-resistant CML patients analyzed. The use of TCDF probe for cytogenetic follow-up in CML patients was found to be useful in identifying BCR-ABL1 related aberrations. The identified patterns in this study, can serve as a reference material for I-FISH signal interpretation using TCDF probe.

Aims: To assess the efficacy and safety of sunitinib in Chinese patients with imatinib-resistant or -intolerant gastrointestinal stromal tumors (GISTs), and evaluate the impact of genotype on sunitinib efficacy. Materials & methods: In a single-arm retrospective study, 55 patients with recurrent or metastatic GISTs who were resistant or intolerant to prior imatinib treatment received sunitinib for at least one treatment cycle. Results: The median progression-free survival was 35 weeks (95% CI: 24.6–45.4) in patients who received sunitinib 37.5 mg/day as a continuous daily dose versus 30 weeks (95% CI: 12.8–47.2) in those who received sunitinib 50 mg/day as a 4-weeks-on, 2-weeks-off (4/2) schedule (p = 0.707). The median overall survival of all patients was 86 weeks (95% CI: 75.0–97.0). Patients with KIT exon 9 mutations had a significantly longer progression-free survival compared with those with KIT exon 11 mutations and patients with wild-type GISTs (p = 0.022). Sunitinib therapy was well tolerated, with most adverse events rated as grade 1 or 2 in severity. The sunitinib 37.5 mg/day continuous daily dose schedule was better tolerated by Chinese GIST patients than the 50 mg/day 4/2 schedule. Conclusion: Sunitinib was effective and well tolerated in Chinese patients with imatinib-resistant or -intolerant GISTs. Patients with KIT exon 9 mutations showed the best efficacy. A 37.5 mg/day continuous daily dose sunitinib dosing schedule appears to be the optimal choice for Chinese patients due to a decreased incidence of adverse events.

Dynamics of the emergence of dasatinib and nilotinib resistance in imatinib-resistant CML patients